JPH07192593A - Alloy type thermal fuse and its manufacture - Google Patents

Abstract

PURPOSE:To provide an alloy type thermal fuse having a sufficient small size in which the tentative fixing of lead wires, the solid fixing of lead wires, and a safe sealing property, in the manufacture can be guaranteed, and the recontinuety immediately after the operation can be prevented so as to cut off the power feeding surely, by making the alloy type thermal fuse with a flat case type and a radial type, as the object. CONSTITUTION:By bending the intermediate parts 21 of lead wire parts in a case 1, the interval L2 between leads at the case opening side is made wider than the interval L1 between leads on a low melting point fusible metal piece 3 side, and the lead wires 2 are put in contact with the inner surfaces 12 of both width ends of the case 1. An insulating type adhesive 5 is filled at the thickness at least reaching the bendings 21 of the above lead wires 5 into a recessed curving surface, the creeping distance L3 between the leads at the above recessed curving surface is set 1.05 times or more of the linear distance L2 between the roots 20 and 20 of both read wires. In the manufacturing, the case is covered by squeezing between the lead wires.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat case radial type alloy type temperature fuse and a method for producing the same.

[Prior art]

In an alloy type temperature fuse using a low melting point fusible alloy piece for a fuse element, when an electric device to be protected by the temperature fuse generates heat due to overcurrent, the heat generated by the fuse -By cutting the fuse element, the power to the equipment is cut off to prevent abnormal heat generation or fire of the equipment.

As a conventional type of such an alloy type temperature fuse, a flat case shown in (a) of FIG. 4 and (b) of FIG. 4 [a cross-sectional view taken along line (a) of (b) of FIG. 4] is used. Radial types of formula are known. 4A and 4B, 1'is a flat case having an opening 11 'at one end, 2'and 2'are a pair of lead wires, and 3'is a lead wire. 4'is a flux applied to the low melting point soluble metal piece 3 ', and 5'is an adhesive filled and solidified in the opening 11' of the flat case 1 '. is there.

This flat case type alloy type temperature fuse
In order to manufacture the same, a low melting point fusible metal piece is bridged between a pair of juxtaposed lead wires, a flux is applied to the low melting point fusible metal piece, and the flux is applied on the low melting point fusible metal piece. A flat case having an opening at one end is covered from the opening, and the opening is filled with an adhesive and solidified.

In this case, the spacing between the lead wires is set to be slightly wider than the inner width of the case on the case opening side.
A bent portion [21 'in FIG. 4 (a)] is formed on the lead wire, the case is elastically supported by the lead wire, and the case is temporarily fixed. Under the condition, the case opening is filled with the adhesive and solidified.

The operating mechanism of the alloy type temperature fuse is that the low melting point fusible alloy piece is melted by the heat generated due to the overcurrent of the electric equipment, and the molten metal coexists with the surface under the coexisting flux. It is spheroidized due to energy, the molten metal is divided by the progress of this spheroidization, and when the arc generated at the initial stage of the division is no longer sustained due to the increase of the division distance, the interruption of the current supply is terminated. It is in.

[0007]

In the above-mentioned case type alloy type temperature fuse, the binding strength between the lead wire and the filling and solidifying adhesive is relatively low, and the lead wire is stretched. It is easily removed by a force or a twisting force, and the sealing property at the interface between the lead wire and the adhesive is easily deteriorated.

Therefore, as shown in FIG. 5, the lead wire 2 '
The solidified adhesive 5'filling at least a part of the bent portion 21 'of
If it is embedded inside, the lead wire bent portion 21 'will become a lead wire 2'.
It effectively works as a resistance against the pulling force or the twisting force acting on the lead wire 2'and the pulling resistance and the sealability of the lead wire 2'can be expected to improve. However, it is avoided that the creepage distance between the lead wires 2 ′ and 2 ′ on the inner surface of the filled and solidified adhesive 5 ′ decreases from L ₃ ′ in FIG. 4A to L ₃ ″ in FIG. I can't.

As described above, in the operation of the alloy type temperature fuse, the molten fuse element (low melting point soluble metal piece) is divided by the spheroidization based on the surface energy, and the division interval is Since the arc continues until reaching a predetermined distance, carbonization of the flux by the arc and adhesion of this carbonized flux to the inner surface of the filling and solidifying adhesive are unavoidable.

However, as shown in FIG. 5, when the creeping distance between the lead wires on the inner surface of the filling and solidifying adhesive is short and carbonized flux adheres to the creeping surface, the creeping insulation strength between them is extremely low. Even if the above arc disappears, a discharge occurs along the creepage due to the circuit voltage that acts between the lead wires, re-conducting between the lead wires, and reliable current interruption can be guaranteed. Absent.

However, if the inner width of the case is widened, the creepage distance between the lead wires on the inner surface of the filling and solidifying adhesive can be lengthened, and this disadvantage can be eliminated, but the size of the temperature fuse is increased. Inevitable.

The object of the present invention is to provide a flat case type radial type alloy type temperature fuse, which is temporarily fixed by a lead wire of the case at the time of manufacturing, and has a strong lead wire. It is an object of the present invention to provide a sufficiently small alloy-type temperature fuse which can secure fixing and stable sealing properties and can surely shut off by eliminating insulation failure.

[0013]

In the alloy type temperature fuse according to the present invention, a low melting point fusible metal piece bridged between a pair of parallel lead wires has an opening at one end. In the temperature fuse, which is accommodated in the opening through the opening, and the insulating adhesive is filled and solidified in the opening, the low melting point soluble metal is formed by bending the middle portion of each lead wire portion in the case. The spacing between the lead wires on the case opening side is made wider than the spacing between the lead wires on one side,
Further, each lead wire is brought into contact with each inner side surface of both ends of the width of the case, and the insulating adhesive is filled to a thickness reaching at least the bent portion of the lead wire. Due to the concave curved surface, the creepage distance between the lead lines on the concave curved surface is 1. The linear distance between the roots of both lead lines on the concave curved surface.
The configuration is characterized by being set to be 05 times or more, preferably 1.10 times or more.

The structure of the present invention will be described below with reference to the drawings. 1A is an explanatory view showing a configuration example of an alloy type temperature fuse according to the invention described in claim 1, and FIG. 1B is a cross-sectional view taken along the line RO in FIG. . In FIG. 1A and FIG. 1B, reference numeral 1 is a flat case having an opening 11 at one end. This case is
It may be made of synthetic resin such as ceramics or phenol resin. 2 and 2 are a pair of parallel lead wires, 3 is a low melting point soluble metal piece bridged by welding or brazing between the lead wires 2 and 2, 4 is a low melting point soluble Each of the fluxes applied to the metal pieces is shown, and the low melting point fusible metal pieces 3 applied by the flux are contained in the case 1. A eutectic alloy can be used for the low melting point metal piece 3, and an activator-added rosin can be used for the flux 4.

In each lead wire 2 described above, the case 1
The intermediate portion 21 in the inside is bent so that the distance L ₀ between the lead wires on the case opening 11 side is wider than the distance L ₁ between the lead wires on the low melting point metal piece 3 side. Further, each lead wire 2 is in contact with each inner side surface 12 at both width ends of the case 1.

Reference numeral 5 denotes an insulating adhesive, for example, an epoxy resin, which is filled and solidified in the case opening 11, the inner surface of which reaches at least the bent portion 21 of the lead wire 2, and the lead wires 2, 2 The inner surface portion between them is a concave curved surface 51. It is also possible to fill and solidify the adhesive 5 so that the lead wire bent portion 21 is completely embedded, as shown in FIG. The concave curved surface 51 of the filling adhesive 5 has a creepage distance L ₃ between the lead wires 2 and 2 on the concave curved surface 51, and a linear distance between the roots of the lead wires 2 and 2 on the concave curved surface 51. (Shortest distance) It is set to be 1.05 times or more, preferably 1.10 times or more of L ₂ .

In the above, the reason why the adhesive 5 is filled and solidified in the case opening 11 so as to reach at least the bent portion 21 of the lead wire 2 is that at least a part of the bent portion 21 is filled and solidified and bonded. This is because it is embedded in the agent 5 and the bending portion 21 effectively acts as a resistance against a tensile force or a twisting force acting on the lead wire 2. In this case, if the inner surface of the filled and solidified adhesive 5 is flat, the creepage distance between the lead lines on the inner surface is significantly shortened (the creepage distance in this case is L ₂ described above). A concave curved surface is formed, and the creepage distance L ₃ between the lead lines is 1.05 times or more of the above L ₂ , preferably 1.10.
The creepage distance between the lead wires is guaranteed to be more than double (note that the greater the depth of the depression of the concave curved surface 21 is, the more advantageous it is to increase the creepage distance, but the filling thickness is increased as a whole. As it becomes thinner as
It is desirable that the creepage distance L ₃ between the wires 2 and _{2 be} 1.48 times or less than the above L ₂ .

In the method of manufacturing the alloy type temperature fuse according to the second aspect, as shown in FIG. 3A, the lead wire 2 having the bent portion 21 is provided outside the wide space portion. Interval L ₄
Slightly wider than the inner width L _{5 of the} sleeve 1 and arranged side by side, the lead wire 2,
A low melting point fusible metal piece 3 is bridged between the two, flux 4 is applied to the low melting point fusible metal piece 3, and the flat case 1 is squeezed between the lead wires 2 and 2. It is characterized in that it is applied on the melting point-soluble metal piece 3. If the outer spacing L ₄ of the wide spacing portion between the lead wires is set to be much larger than the inner width L _{5 of} the flat case, when the flat case 1 is applied, the distance between the lead wires 2 and 2 is increased. Since there is a fear that the joint portion between each lead wire 2 and the low melting point fusible metal piece 3 will be greatly squeezed and damaged due to a large moment, L ₅ <L ₄ ≦ 1.2 L ₅ In this case, the narrow spacing between the lead wires 2 and 2 may become slightly narrower toward the bent portion 21 as shown in FIG.

After the flat case 1 is applied in this manner, a high-viscosity adhesive such as an epoxy resin is filled into the opening with the case opening facing upward, and then the case opening is opened. The filling adhesive is cured with the side facing downward. In this case, in the adhesive at the center of the case opening,
The sagging due to its own weight is more likely to occur than the adhesive on both sides, and the inner surface of the filling adhesive has a concave curved surface as shown in (b) of FIG.
The degree of this concave curved surface can be adjusted by the time for which the case opening is kept in the downward direction.

The dimensions of each part of the flat case radial type alloy type temperature fuse are usually as follows. 1A and 1B, the width a of the flat case is 3.5 mm to 7 mm, and the length b is 3 mm to 9 as well.
mm, similarly thickness c: 1.5 mm to 3.0 mm, similarly case wall thickness d: 0.4 mm to 1.5 mm, lead wire diameter D ₁ : 0.3 mm to 1.0 mm, low melting point possible Diameter D _{2 of the} molten metal piece: 0.2 mm to 1.0 mm.

[0021]

As shown in FIGS. 3 (a) and 3 (b), the lead wires 2 having the bent portions 21 are arranged in parallel, and the lead wires 2 and 2 are provided.
The outer space L ₄ of the wide space between the two is made slightly wider than the inner width L _{5 of the case} 1, and the low melting point fusible metal piece 3 is bridged between the lead wires 2 and 2 to form a flat case. The case 1 can be temporarily fixed to the lead wires 2 and 2 by covering the low melting point metal piece 3 by squeezing the lead wires 2 and 2 between the lead wires 2 and 2. The case 1 can be stably held at a predetermined position until the opening is filled with the adhesive and solidified, and the temperature fuse can be smoothly manufactured.

Further, as shown in (a) and (b) of FIG. 1, since at least a part of the bent portion 21 of the lead wire 2 is embedded in the filling and solidifying adhesive 5, the lead The bent portion 21 effectively acts as resistance against the removal or rotation of the wire 2.
Even if a pulling force or a twisting force acts on the lead wire 2, the fixed state of the lead wire 2 can be maintained sufficiently stable, and the sealability can be well ensured.

Further, when the carbide of the flux due to the arc adheres to the inner surface of the filling and solidifying adhesive 5 during the operation of the temperature fuse, the creepage distance L ₃ between the lead wires 2 and 2 on the inner surface of the filling and solidifying adhesive 5 is increased. Is made sufficiently long by forming a concave curved surface 51 on its inner surface, so that the insulation resistance of the creeping surface can be sufficiently ensured, and re-conduction between the lead wires after the arc disappears can be well prevented, which is reliable. It is possible to secure excellent current interruption characteristics.

Furthermore, since the inner surface of the filled and solidified adhesive 5 is the concave curved surface 51, carbonization due to the contact of the inner surface 51 with the arc can be eliminated.

[0025]

【Example】

Example 1 In (a) and (b) of FIG. 1, the flat case 1 has a width a: 5.2 mm, a length b: 4 mm, and a thickness c: 2.
2 mm, case wall thickness d: 0.8 mm, a ceramic case is used, and the lead wire 2 has a diameter D ₁ : 0.53 mm.
I used a copper wire. As the low melting point soluble metal piece 3, a eutectic alloy wire rod (round wire) having a diameter D ₂ : 0.4 mm and a melting point of 126 ° C. was used. The distance L ₁ between the lead wires on one side of the low melting point soluble metal was 2.3 mm. Softening point 4 for flux 4
Rosin with activator at 0 ° C. was used. An epoxy resin liquid is used for the adhesive 5, and the creeping distance L ₃ between the lead wires 2 and 2 of the concave curved inner surface 51 of the filling adhesive 5 is set to the value of both lead wires 2 and 2 of the concave curved surface 51. Straight line distance L ₂ between the roots 20, 20
Was set to 1.10 times. The straight line distance L ₂ was 2.4 mm (confirmed by fluoroscopy).

Embodiment 2 Compared to Embodiment 1, the depth of the recess of the concave curved inner surface 51 of the filling adhesive 5 is made deeper, and the creeping distance L ₃ between the lead wires 2 and 2 on the concave curved inner surface 51. Was the same as in Example 1 except that the distance was 1.4 times the distance L ₂ .

Comparative Example Example 1 except that the inner surface of the filling adhesive was made substantially flat and the creepage distance between the lead wires on the inner surface was 2.4 mm.
Same as.

With respect to these example products and comparative example products (50 samples in each case), while energizing at 250 volts and 5 amps, the samples were immersed in silicone oil at a temperature of 128 ° C. When all of the example products were able to operate reliably without the occurrence of insulation defects, 24 out of 50 of the comparative example products had insulation defects.

[0029]

The alloy-type temperature fuse and the method for manufacturing the same according to the present invention have the above-described structure and have a low melting point due to the bending of the middle portion of each lead wire portion in the case. The spacing between the lead wires on the case opening side is made wider than the spacing between the lead wires on one side of the fusible metal, and each lead wire is in contact with each inner side surface of the width ends of the case. The insulating adhesive is filled and solidified at least to a thickness that reaches the bent portion of the lead wire, thereby increasing the fixing strength against the tensile force and the twisting force of the lead wire and the seal stability, and manufacturing. Despite guaranteeing the temporary fixing of the lead wire in the case at that time, the creeping distance between the lead wires on the concave curved surface is sufficiently increased by making the inner surface of the adhesive filling concave. Since it is secured, even if carbonized flux adheres to this inner surface during operation of the temperature fuse, defective insulation is eliminated. I can guarantee reliable current interruption by.

Therefore, according to the present invention, the lead wire is temporarily fixed in the case at the time of manufacturing, and the stable lead wire is secured.
It is possible to provide a flat-case radial type alloy-type temperature fuse capable of guaranteeing the reliability of the casing and capable of surely interrupting the electric current by eliminating the insulation failure immediately after the operation.

[Brief description of drawings]

FIG. 1A is an alloy-type temperature fuse according to the present invention.
FIG. 1 (b) is an explanatory view showing an embodiment of FIG.
FIG.

FIG. 2 is an explanatory view showing another embodiment of the alloy type temperature fuse according to the present invention different from the above.

3 (A) and 3 (B) are explanatory views showing a method of manufacturing the temperature fuse according to the present invention, and FIG.
Shows the stage before the case is applied, and FIG. 3B shows the stage after the adhesive is filled.

FIG. 4A is an explanatory view showing a conventional example, and FIG. 4B is a cross-sectional view taken along line B-B of FIG.

FIG. 5 is an explanatory diagram showing another conventional example different from the above.

[Explanation of symbols]

1 case 11 case opening 12 both sides in case opening 2 lead wire 21 bent part 3 low melting point fusible metal piece 5 filling solidification adhesive 51 concave curved surface L ₃ concave curved lead Li in the creeping distance L ₂ concave surface between the lines - the linear distance between the base of the lead wire

Claims (2)

[Claims] 1. A low melting point fusible metal piece bridged between a pair of juxtaposed lead wires is accommodated from an opening in a case having an opening at one end, and an insulating adhesive is placed in the opening. In the temperature fuse to be filled and solidified, due to the bending of the middle portion of each lead wire portion in the case, the case opening side rather than the interval between the lead wires on one side of the low melting point fusible metal The spacing between the lead wires of is widened,
Further, each lead wire is brought into contact with each inner side surface of both ends of the width of the case, and the insulating adhesive is filled to a thickness reaching at least the bent portion of the lead wire. Due to the concave curved surface, the creepage distance between the lead lines on the concave curved surface is 1. The linear distance between the roots of both lead lines on the concave curved surface.
Alloy type temperature fuse characterized by being set to 05 times or more. 2. The method for manufacturing an alloy type temperature fuse according to claim 1, wherein the lead wire having the bent portion is formed such that the outer space of the wide space is slightly wider than the inner space of the case. Then, the low melting point soluble metal piece is bridged between the lead wires, the flux is applied to the low melting point soluble metal piece, and the case is applied onto the low melting point soluble metal piece. A method for manufacturing an alloy type temperature fuse characterized by the above.